tach dash question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

longhorn71 · 01-16-2005, 05:15 AM

I have a 1981 blazer.I want to put a tach cluster in it.It has a gauge cluster in it now.what do in need to swap this cluster in to it?IS The wiring harness the same exepted for the tach wiring?The cluster I have is from a 75 truck will it still work and macth the wiring in the 81?any help would be great Thanks DEAN

TrainD5115 · 01-16-2005, 11:37 AM

You can't use 75 gauges in a 81 truck. For further info on why look here:http://www.73-87.com/7387garage/inte...achometers.htm

Russell · 01-16-2005, 04:34 PM

Hey Dean!

Like mentioned earlier, the wiring between the 75 cluster and the 81 Blazer won't be the same. You can, however make it work if you wanted to take the time

You can replace the amp gauge with a volt gauge, and do some re-wiring on the truck's factory harness to make it all work. You'd need to modify how the volt gauge is hooked up, and you'd need to do some re-pinning of the connector to make up for differences between the two years. As far as the mechanical oil gauge goes, I can give you a sending unit / some piping to hook it up to your engine. Mechanical oil gauges are way better than electric ones anyways (I intend to make the same swap on my truck, my electric one bounces all over the place, and it's reading is affected on the amperage drain on the electrical system, turning on the headlights throws it off by 10 PSI, easy)

longhorn71 · 01-17-2005, 12:44 AM

thanks Russell, for the help,as I do not know the 73-87 models well.

DBLSPRT68 · 01-17-2005, 02:48 AM

Dean, your best thing to do is find a 79 and up tach cluster. They are on Ebay, or even people on here have them for sale. I have a 73-75 tach cluster in my attic that I bought off Ebay(4 years ago), cause the guy said it would work

! Now, I know the difference. They are out there, you may have to pay more for them, but they'll work in your truck.

77gmcjoe · 01-17-2005, 09:56 AM

I think it's '78 and up, actually. And I don't know if it matters to ya, but if you want the same gauge faces as you have now (same style numbers and needles), you'd have to find an '80 or up.

Russell · 01-17-2005, 11:02 AM

There is an awesome writeup about interchangeability and such on www.73-87.com

BTW Joe -- You are right, 78 bolts right in, and still has the blue faced tach / speedo with the 160 km/h (100 mph) speedometer

01-16-2005, 05:15 AM	#1
longhorn71 Senior Member Join Date: Sep 2004 Location: CANADA Posts: 1,681	tach dash question I have a 1981 blazer.I want to put a tach cluster in it.It has a gauge cluster in it now.what do in need to swap this cluster in to it?IS The wiring harness the same exepted for the tach wiring?The cluster I have is from a 75 truck will it still work and macth the wiring in the 81?any help would be great Thanks DEAN

01-16-2005, 11:37 AM	#2
TrainD5115 North Coast, baby! Join Date: Jun 2004 Location: Toledo, OH Posts: 437	You can't use 75 gauges in a 81 truck. For further info on why look here:http://www.73-87.com/7387garage/inte...achometers.htm __________________ Brad 79 Scottsdale C20 350/350 3.73's Still running full CA smog gear!

01-16-2005, 04:34 PM	#3
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	Hey Dean! Like mentioned earlier, the wiring between the 75 cluster and the 81 Blazer won't be the same. You can, however make it work if you wanted to take the time You can replace the amp gauge with a volt gauge, and do some re-wiring on the truck's factory harness to make it all work. You'd need to modify how the volt gauge is hooked up, and you'd need to do some re-pinning of the connector to make up for differences between the two years. As far as the mechanical oil gauge goes, I can give you a sending unit / some piping to hook it up to your engine. Mechanical oil gauges are way better than electric ones anyways (I intend to make the same swap on my truck, my electric one bounces all over the place, and it's reading is affected on the amperage drain on the electrical system, turning on the headlights throws it off by 10 PSI, easy) __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

01-17-2005, 02:48 AM	#5
DBLSPRT68 Registered User Join Date: Nov 2000 Location: Ft. Mill, SC USA Posts: 931	Dean, your best thing to do is find a 79 and up tach cluster. They are on Ebay, or even people on here have them for sale. I have a 73-75 tach cluster in my attic that I bought off Ebay(4 years ago), cause the guy said it would work ! Now, I know the difference. They are out there, you may have to pay more for them, but they'll work in your truck. __________________ PROJECT TRUCK: 1985 SWB C10 Silverado Black/Charcoal, 1990 V2500 Suburban, 2018 Suburban, 2005 GMC 2500HD CCSB, 2014 Toyota Camry SE, HAD.....1968 Camaro RS/SS Family owned since new; 350 3 speed SOLD

01-17-2005, 09:56 AM	#6
77gmcjoe What do we get for $10? Join Date: Oct 2004 Location: Beardstown, Illinois Posts: 340	I think it's '78 and up, actually. And I don't know if it matters to ya, but if you want the same gauge faces as you have now (same style numbers and needles), you'd have to find an '80 or up. __________________ 1977 GMC K25 400/400/205 1989 Chevy Suburban R1500 350/700R4 (work beater) 1994 Chevy K3500 dually 454/4L80 1996 Corvette LT4 350/ZF 6 speed 2000 Bonneville SSEI Supercharged 3.8 Liter V6 1966 Chevelle 2 door sedan (Needs major repair )

01-17-2005, 12:44 AM	#4
longhorn71 Senior Member Join Date: Sep 2004 Location: CANADA Posts: 1,681	thanks Russell, for the help,as I do not know the 73-87 models well.

01-17-2005, 11:02 AM	#7
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	There is an awesome writeup about interchangeability and such on www.73-87.com BTW Joe -- You are right, 78 bolts right in, and still has the blue faced tach / speedo with the 160 km/h (100 mph) speedometer __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

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